Dot printers produce a printed image by depositing a pattern of individual dots of ink upon a recording medium, such as a sheet of paper. Ideally, if the individual dots are sufficiently small and closely spaced, only the overall image, and not the individual dots, are perceived by the human eye.
However, depending on the relative size of the smallest detail of the overall image and the size of the individual dots, certain irregularities may be perceived due to the discrete nature of the dots and due to the inherent nature of the printing process. For example, undesirable stepping (quantization) and jagged edges are generally apparent when the image consists of a diagonal line at a slight angle to the print direction, or a diagonal line at a steep angle to the print direction. Jagged edges are also noticeable in images with curved lines.
Thus, what is needed is a print image enhancement system for providing a more pleasing dot image. This print enhancement system should meet three important criteria. Firstly, the appearance of the final image must be improved in most cases with only minimal degradation in the remainder of cases. Secondly, the print image enhancement system must have a minimal impact on printer throughput. Thirdly, the print image enhancement system must be low cost and compatible with existing systems.